In International Telecommunication Union Radio communication sector (ITU-R), a standardization task for International Mobile Telecommunication (IMT)-Advanced, that is, the next-generation mobile communication system after the third generation is in progress. IMT-Advanced sets its goal to support Internet Protocol (IP)-based multimedia service at a data transfer rate of 1 Gbps in stop and slow-speed moving states and of 100 Mbps in a fast-speed moving state.
For example, 3rd Generation Partnership Project (3GPP) is a system standard to satisfy the requirements of IMT-Advanced and is preparing for LTE-Advanced improved from Long Term Evolution (LTE) based on Orthogonal Frequency Division Multiple Access (OFDMA)/Single Carrier-Frequency Division Multiple Access (SC-FDMA) transmission schemes. LTE-Advanced is one of strong candidates for IMT-Advanced.
One of systems being taken into consideration in the next-generation wireless communication system is an Orthogonal Frequency Division Multiplexing (OFDM) system capable of attenuating an Inter-Symbol Interference (ISI) effect with low complexity. In OFDM, serially inputted data symbols are converted into N parallel data symbols and are carried on N separated subcarriers and then transmitted. The subcarriers maintain orthogonality in the frequency domain. Each of the orthogonal channels experiences independent frequency selective fading, and thus ISI can be minimized because an interval between transmitted symbols is lengthened. Orthogonal Frequency Division Multiple Access (hereinafter referred to as OFDMA) refers to a multiple access method of realizing multi-access by independently providing some of available subcarriers to users, in a system using OFDM as a modulation method. In OFDMA, frequency resources called subcarriers are provided to each of users, and the frequency resources are commonly independently provided to a plurality of users so that they do not overlap with one another. As a result, frequency resources are exclusively allocated to users.
In an OFDMA system, frequency diversity for multiple users can be obtained through frequency selective scheduling, and subcarriers can be allocated in various forms according to a permutation method for the subcarriers. Furthermore, the efficiency of a spatial region can be increased through a spatial multiplexing scheme using multiple antennas. In order to support the various schemes, a control signal must be transmitted between user equipment and a base station. The control signal includes a Channel Quality Indicator (CQI) reporting a channel state transmitted from user equipment to a base station, an Acknowledgement/Not-acknowledgement (ACK/NACK) signal, that is, a response to data transmission, a bandwidth request signal to request the allocation of a radio resource, precoding information in a multiple antenna system, antenna information, and so on. The control signal is transmitted through a control channel.
Meanwhile, technology being taken into consideration in the next-generation wireless communication system includes a Relay Station (RS). A relay station functions to extend cell coverage and improve transmission performance. When a base station serves user equipment placed at the coverage boundary of the base station through a relay station, there is an advantage in that cell coverage is extended. Furthermore, if a relay station improves the transmission reliability of a signal between a base station and user equipment, transmission capacity can be increased. If user equipment is placed in a shadow region although it is placed within the coverage of a base station, the user equipment may use a relay station. In a wireless communication system including the relay station, OFDMA may be used as modulation technology.
In a relay station, a frequency band used when a signal is transmitted to a base station may be identical with a frequency band used when a signal is received from relay station user equipment connected to the relay station. Alternatively, in a relay station, a frequency band used when a signal is received from a base station may be identical with a frequency band used when a signal is transmitted to relay station user equipment. It is difficult for a relay station to perform the transmission and reception of signals, included in the same frequency band, at the same time owing to self-interference. Accordingly, a relay station has to transmit and receive signals included in the same frequency band by temporally separate transmission and reception from each other.
In a wireless communication system including a relay station, a resource allocation method for a radio resource, for example, a frame is problematic. A method in which a relay station transmits data using a frame allocated thereto as resources is problematic.